Quote:
Originally Posted by Triple Jim
Of course I still disagree that shorting the stator in a permanent magnet alternator causes it to get hot. Here's a discussion that backs up what I've said... that a dead short of the stator's output from a shunt regulator does not cause extra heating due to power dissipation:
https://www.physicsforums.com/thread...system.839582/
Some quotes from that discussion:
That last sentence sums it up nicely. With a shunt regulator, the alternator is not putting out full power all the time! |
Half of those nerds have never even touched a bike! Here's another fun one from that forum:
https://www.physicsforums.com/thread...e-down.972994/ . Those nerds needs to get off their armchairs and go back to actual engineering school. The thing people don't realize is linear-regulator circuit simply doesn't short stator AC-input to ground, that's not how circuit is designed or wired! They are talking about circuits that actually don't exist. AC-output from stator is always connected to rectifier's input 1st. Then shorting
only occurs later in rectifier stage when it's DC. Here's intro to linear-regulators:
https://en.wikipedia.org/wiki/Linear_regulator
https://www.digikey.com/en/maker/blo...age-regulators
Get hands-on empirical data from actual bike. I used AC clamp on current-meter on stator output. At no time is output zero on any phase because regulator regulates output voltage in 3-way voltage-divider split, not short input to zero. If you cut input 20-VAC or 40-VAC or 60-VAC to 0-VAC, how are you going to get 14-VDC out of it?
I also have clamp-on DC current meter on regulator output and dump wires. The sum of DC outputs is
always ~15 amps regardless of load on system. High-power high-beams on or off (+5 amps), heated gloves (+5amps). Only thing that changes is balance between output vs. dump: 5+10, 8+8, 10+5, etc. Total is
always same.
My next test is to use infrared thermometer to measure stator temps at various loads. Will be secondary confirmation of output measured earlier.
Put some meters on actual bike. Also look up how linear/shunt regulators work. They're a voltage divider/ladder. Well, now I know where to post all my measurements and make some of those armchair nerds get their hands dirty.
* BTW- what you're describing with quick on/off chopping by shorting is a switching-regulator. Similar to more modern SH775 and SH847 series regulators. The rapid on/off switching cuts off output and voltage is adjusted by PWM. That you can see with oscilloscope. There's absolutely
zero switching or PWM going on with OEM shunt regulators on these bikes.